Alter your build slightly to something like this, gives you more sta/mana and spell power instead of where u put the points originally, ofc it depends a little what your gear is like, if you have good +spell health and mana pools then some demonology talents will enchance this, if your stats are poor I'd be tempted to put some points into affliction as you might need improved life tap to regen some mana.
http://www.worldofwarcraft.com/info/classes/warlock/talents.html?0000000000000000000000350020003000000000000505000512200510531051
Don't try to vw tank with destro it's pointless, the name of the game is to dps the mobs down before they can do you any damage usually with imp to add a little dps, and boost your hp with blood pact, the most effective way of doing this is using a high dmg cast as an opener from max range usually shadow bolt, then fit in as much dps as you can while it comes to you. If its still alive, time to fear. Alternatively you can seduce nuke if the mob is humanoid with the succi, dps at max range no dots, seduce when it gets too close, run to max range, dps rinse repeat.
Having said that you got to decide yourself what pet to use for what situation, how to pull, what to pull, can the mob(s) be feared? learn how to play by making mistakes and trying out new ways of dealing with different mobs, it's the best way.
Edited, Apr 22nd 2007 6:07pm by mangiacapra
Edited, Apr 22nd 2007 6:12pm by mangiacapra